The current Kambara Kisen website shows a different flag, still in the national colours
- English version here.

From the company history (highlights only). Founded 1903 by
Katsutaro Kambara (coastal shipping: transport of coal). 1944, founding of
Setonaikai Senpaku renamed Kambara Kisen (Tokyo) four years later. Ships
built by Tsuneishi - operated are car, multipurpose, and bulk carriers;
later, container ships. Kambara Marine KK founded in 1978. 1995, head
office moves from Tokyo to Hiroshima. Various subsidiaries are established.
Growing transportation business between Japan and China (inland included).
2003, Tsuneishi centenary.

As to the relation between Kambara and Tsuneishi (the first one consistently
being subtitled ‘Tsuneishi Holdings Corporation’), see these links - the
first in Japanese,
the second one in
English,
concerning the company logo:

Quoting from English version, edited:

"(…) among the (first) four (Kambara) sailboats, was one called the
"Tenshamaru," which was particularly lucky and generated good profits.
Including the "No. 4 Tenshamaru" ordered by Kambara Kisen Co., Ltd.,
Tsuneishi Corporation built many "Tenshamaru" ships.

We have built a lot of medium-class steel ships crowned with the letter "
(ten)" which have contributed to the development of not only the Tsuneishi
Group but also Japan's shipping industry. In the hope of sharing the good
fortune brought by the "Tenshamaru", we chose the letter [representation unavailable]
and "V", " as our company logo.

Since we chose our present logo in 1949, many of our Group companies have
adopted the [representation unavailable] mark as their company logos.
This logo now symbolizes the Tsuneishi Group."

Leaving the 2003 centenary logo aside, and having to refer to the Japanese
version for the character missing in the English text it is clear that the house flag shown on the
site reflects this.

The Tsuneishi Group comprises an impressive
list of companies (among them shipbuilding, ferry, investment, steel, etc.)
found here.Jan Mertens, 3 June 2007

I guess that this is "天", which reads "tiān" in pinyin.

This page
also mentions a new logo, also based on "天" but looking
like "x ̌" (an "x" with caron on it). It is made from sharp triangles
and placed in white on a navy blue background, with lettering "Tsuneishi"
in bold italic sanserif capitals.

Though this logo change surely affected corporate flags in use, I doubt
that the change was reflected immediatly in the houseflag practice. Either
for legal necessity of registering a shipping houseflag,
or because of seamen’s infamous stubbourness, houseflags seem to keep old
designs and logos long after parent companies changed their visual
identity on land.

The company includes two of the not many differences between
the Hepburn and the Cabinet romanizations of Japanese: It is "Tuneisi"
according to Cabinet rules. (Another example is
Mitubisi.)António Martins-Tuválkin, 19 August 2007

Kanko Kisen

Kanko Kisen is a Japanese ferry company, member of a group also comprising -
among others - Hankyu Ferry. Website, Japanese only:
http://www.kankokisen.co.jp/.
The company seat, Shimonoseki, is situated in the S.W. of Honshu, the largest
island of Japan. Additional offices are located in Osaka and Tokyo.
As stated on http://www.interq.or.jp/:

Kanko Kisen is the nucleus of the SHK Line Group, which is itself a joint
venture between Hankyu Ferry,
Shin Nihonkai Ferry, Kampu Ferry, Orient Ferry,
Nishi Nihon Kisen, Japan Cruise Line (Venus Cruise), etc.
The history of regular Japanese long distance car ferry services started with
Hankyu Ferry's Ferry Hankyu (4,978 G/T) in 1968. The mixture of a growing
economy and congested roads resulted in the concept of ferry-based traffic
promoted by Mr. Hoshu Iriya, the president of Kanko Kisen, often referred to as
the father of Japanese long distance car ferries.

The fleet page
shows Hama Yuu, Seong Hee, Utopia, Utopia 2 and two more - since the
liveries often differ I suppose Kanko Kisen operates but perhaps not owns them,
or vice versa. In general these ferries carry passengers - at least one
line links Shimonoseki to China - but some are equipped for ro/ro as well.
On a white field, a voided diamond with contour line in red enclosing a red initial
‘K’.
There is also a Japanese
Wikipedia
page concerning this firm (founded in 1948)Jan Mertens, 12 October 2008